① The access floor construction preparation: level of the site, clean up debris, and deal with the soft soil when necessary.

② Pile lofting: check and retest the relevant wire coordinates and water level base piles delivered by the design unit, measure the hole pile position and elevation, and set up protective piles for the purpose of inspection and use.

③ The access floor guard is welded with a 4MM steel plate, the inner diameter is the diameter of the hole pile plus 30CM, and the length is 2.0 m. The protection cylinder is buried in the dry land, and the top of the protection cylinder is more than 0.3M above the ground to prevent the inflow of surface water. When burying, ensure that the shell is vertical, the top surface is level, and the center position of the shell is accurate. The bottom end of the shell should be buried in the dense soil layer, and the surrounding clay should be rammed and compactly filled.

④ For the drilled piles within the distance of 5M adjacent piles, drilling should be done 24 hours after the completion of the front concrete pile and the final setting degree, so as not to affect the quality of the pile. Drilling mud wall protection, poor soil quality (sand, loose soil) can be added in the mud bentonite and sodium carbonate, in order to increase the mud viscosity and wall protection ability.

⑤The access floordrilling: drilling operations continue, shall not be interrupted, and often pay attention to the changes in the formation, drilling or into the sand layer, at a low speed, strengthen the wall protection, to prevent drilling in the hole.

⑥ Clear hole: clear hole, should keep the height of the water head in the hole, prevent slump hole, hole bottom sediment thickness is less than 10CM, using the pumping method to clear hole.

⑦The access floor final hole inspection: after drilling to the design depth of the hole, the aperture, slope, thickness of mud sediment, check, confirm the technical indicators of the mud in line with the requirements of the following table, before the construction of the next process.